An important goal of the hard disk drive industry is to develop magnetic heads for hard disk drives that provide ever faster data writing speeds, and that allow data to be written with ever increasing areal data storage density, that is, with more bits of data written per unit of disk area.
As is known to those skilled in the art, prior art magnetic head designs include a GMR sensor having a plurality of thin film layers that include a free magnetic layer that is disposed between two hard bias layers. The hard bias layers have relatively high magnetic coercivity and act as a hard magnet to provide a magnetic field that biases the free magnetic layer. Under the influence of this bias magnetic field, the magnetic fields of the free magnetic layer are generally stable and oriented in a single direction.
As the magnetic head passes over various data bit positions along a data track on the disk, the magnetic field of the free magnetic layer rotates in response to the magnetic fields of the data bits of the hard disk. Therefore, to function properly, the magnetic field of the data bits must be stronger than the biasing magnetic field of the free magnetic layer, such that the magnetic field of the free magnetic layer will rotate. Where data bits are made smaller to increase the areal data storage density, the magnetic field of such data bits is likewise decreased. It is therefore desirable to fabricate a GMR sensor in which the biasing magnetic field of the free magnetic layer is reduced, such that the sensitivity of the free magnetic layer is increased and the areal data storage density of magnetic bits of hard disk drives can be increased. The magnetic head of the present invention includes a magnetic biasing layer that is directed towards resolving this problem.